The present invention relates to a process for the preparation of finely divided microcrystalline-to-amorphous metal and/or alloy powders or highly dispersed colloids by the reduction of metal salts with alkali metal or alkaline earth metal hydroxides that are kept in solution in organic solvents by means of specific complex-forming agents. What is further claimed is the use of the powders produced according to the invention in powder technology (Ullmanns Encykl. Techn. Chemie, 4th Edition, Vol. 19, p. 563) or as catalysts in a neat or supported form (Ullmanns Encykl. Techn. Chemie, 4th Edition, Vol. 13, p. 517; further: Kirk-Othmer, Encyclopedia of Chemical Technology, Vol. 19G, pp. 28 et seq.). The colloids prepared according to the invention may be used to apply the metals in the form of fine cluster particles onto surfaces (J. S. Bradley, E. Hill, M. E. Leonowicz, H. J. Witzke, J. Mol. Catal. 1987, 41, 59 and literature quoted therein) or als homogeneous catalysts (J. P. Picard, J. Dunogues, A. Elyusufi, Synth. Commun. 1984, 14, 95; F. Freeman, J. C. Kappos, J. Am. Chem. Soc. 1985, 107, 6628; W. F. Maier, S. J. Chettle, R. S. Rai, G. Thomas, J. Am. Chem. Soc. 1986, 108, 2608; P. L. Burk, R. L. Pruett, K. K. Campo, J. Mol. Catal. 1985, 33, 1).
More recent methods for the preparation of superfine metal particles consist of metal evaporation (S. C. Davis and K. J. Klabunde, Chem. Rev. 1982, 82, 153-208), electrolytical procedures (N. Ibl, Chem. Ing.-Techn. 1964, 36, 601-609) and the reduction of metal halides with alkali metals (R. D. Rieke, Organometallics 1983, 2, 377) or anthracene-activated magnesium (DE 35 41 633). Further known is the reduction of metal salts with alkali metal borohydrides in an aqueous phase to form metal borides (N. N. Greenwood, A. Earnshaw, Chemistry of the Elements, Pergamon Press 1986, p. 190). The coreduction of iron and cobalt salts in water results in the production of a Fe/Co/B alloy having the composition of Fe.sub.44 Co.sub.19 B.sub.37 (J. v. Wonterghem, St. Morup, C.J.W. Koch, St, W. Charles, St. Wells, Nature 1986, 322, 622).